An active server, if disabled from continuing the predetermined operation, takes over the predetermined operation to a standby server, whereby the standby server continuously performs the predetermined operation. For example, if a fault occurs in the process which executes the predetermined operation, the active server gets disabled from continuing the predetermined operation. The process with the occurrence of the fault is terminated, and the active server is forcibly stopped (which is also called a forced panic) whereby the standby server takes over the predetermined operation.
An UNIX-based operating system includes a /proc file system. The /proc file system is stored with text-formatted information about a kernel and an in-execution process. Whether the process exists on a memory or not is checked by monitoring a process structure of the /proc file system in a way that uses a polling-oriented monitoring technique. Then, in the case of detecting that none of the process exists on the memory, the active server is forcibly stopped. A known technique is a technique of acquiring a terminated status of the process (for example, Japanese Laid-Open Patent Publication NO. 2007-133603).